A cathode active material for a secondary battery has lithium impurities such as LiOH and LiCO3 which are present on the particle surface thereof. If these impurities are present in an excessive amount, not only do they cause to make an electrode slurry to be gelated during the production of the electrode slurry in the preparation of an electrode of a lithium secondary battery, but also causes a swelling phenomenon, particularly a lithium ion prismatic or polymer battery expanding, when reacted with the components of an electrolyte introduced in the lithium secondary battery.
Accordingly, there is a need for minimizing the content of lithium impurities present on the particle surface of the cathode active material for a lithium secondary battery.